Method for winding up a thin layer material having a broad width

ABSTRACT

A thin layer material having a large width can be wound up around a winding core by continuously supplying and inserting an elongated continuous yarn-like material, which traverses the thin layer material, in between one wound layer and another to leave a clearance along the inserted yarn-like material. Irregularities in thickness of the thin layer material are absorbed into the clearance, whereby a long length of wide thin layer material can be wound up into a cylindrical form of larger diameter. Further, by making a width to which the yarn-like material is extended, when supplied by reciprocatingly traversing the layer material, larger than the width of the wound thin layer material, and thus supplying the yarn-like material beyond both the edge parts of the thin layer material, the greater portion of thus supplied yarn-like material can be formed into almost wound at first and then arc chords at both the side faces of the wound cylindrical roll of the thin layer material, and the resulting chords cover the side surfaces of the woundup cylindrical roll of the layer material, whereby the side faces of the wound roll are protected through a large number of the yarn-like materials forming said arc chords, and at the same time, deformation, such as telescoping of the wound thin layer material can be prevented, even when loosely wound up and also the successive unwinding can be easily assured.

United States Patent Yazawa et a].

[ 1 July 18, 1972 Polymer Processing Research Institute Ltd., Tokyo,Japan 221 Filed: octs, 1910 2: Appl.No.: 79,091

[73] Assignee:

[30] Foreign Application Priority Data Dec. 9, 1969 Japan ..44/99208[52] U.S. Cl. ..242/54 R, 28/21 [51 Int. Cl ..B65h 75/00 [58] Field 0!Search ..242/54 R; 28/2] [56] Relerenoes Cited UNITED STATES PATENTS2,386,823 l0/l945 Thornburgh ..242/54 R X 3,289,440 l2/l966 Buddecke..242/54 R X 3,32 I ,185 5/l967 Zenke .242/54 R X 3,583,65l 6/1971Schulze et al. ..242/54 R Primary ExaminerStanley N. Gilreath AssistantExaminer-Milton Gerstein Attorney-Fred C. Philpitt [57] ABSTRACT A thinlayer material having a large width can be wound up around a windingcore by continuously supplying and inserting an elongated continuousyarn-like material, which traverses the thin layer material, in betweenone wound layer and another to leave a clearance along the insertedyarn-like material. lrregularities in thickness of the thin layermaterial are absorbed into the clearance, whereby a long length of widethin layer material can be wound up into a cylindrical form of largerdiameter. Further, by making a width to which the yarnlike material isextended, when supplied by reciprocatingly traversing the layermaterial, larger than the width of the wound thin layer material, andthus supplying the yam-like material beyond both the edge parts of thethin layer material, the greater portion of thus supplied yarn-likematerial can be formed into almost wound at first and then are chords atboth the side faces of the wound cylindrical roll of the thin layermaterial, and the resulting chords cover the side surfaces of thewoundup cylindrical roll of the layer material, whereby the side facesof the wound roll are protected through a large number of the yam-likematerials forming said are chords, and at the same time, deformation,such as telescoping of the wound thin layer material can be prevented,even when loosely wound up and also the successive unwinding can beeasily assured.

1 Claim, 4 Drawing Figures Patented July 18, 1972 2 Sheets-Sheet lPatented July 18, 1972 2 Sheets-Sheet 'l FIG.2

METHOD FOR WINDING UP A THIN LAYER MATERIAL HAVING A BROAD WIDTH Thisinvention relates to a method for winding up a thin layer materialhaving a broad width, and more particularly to a method for winding up athin layer material having a broad width, where a thin layer materialhaving a broad width such as a film and thinly spread filament tow,etc., is wound up onto a winding core, which comprises continuouslysupplying and inserting an elongated consecutive yarn-like material,reciprocatingly traversing the thin layer material into between onewound layer and another, even if there is a little irregularity inthickness of the thin layer material; winding up the thin layer materialwhile leaving a clearance along the yarn-like material between the woundup layers thereof, thereby to make the clearance absorb the irregularityin the thickness and make it possible to wind up the thin layer materialinto a roll of cylindrical form, even if the long thin layer material isto be wound up into a roll of larger diameter; making a width to whichthe yarn-like material is extended, larger than the width of the woundthin layer material namely beyond the side edge of thin layer materialwhen supplied by reciprocatingly traversing the layer; and allowing thesupplied portion of the yarn-like material over the width of the woundthin layer material to cover both the side faces of wound cylinder in aform of wound arc chords to protect the side faces of woundup thin layermaterial roll by piled up layers of a large number of arc chords of theyarn-like material as well as protect deformation, such as telescoping,of the wound-up thin layer material, even if the thin layer material iswound up under a low tension and make sure unwinding.

The "thin layer material having a broad width" defined in the presentinvention can include the following materials.

Group A: Yarn and filament layers of organic and inorganic fibersextended to a thin layer, which can be illustrated by:

I. Thin, parallel fiber layer of a large number of parallel fibersprepared in a process for producing a filament tow of artificial fibersin a laterally extended state, for example, 30 50 cm wide in case wherea thickness is 300,000 500,000 denier (d.) in the total denier (d.), andthe parallel fiber layer laterally re-extended to an approximately equalthickness afier bundling said thin, parallel fiber layers in tow form,and further subjected to a towform processing such as heat-treatment,drying, bleaching, drying, crimping, etc.

2. Parallel yarn layer of filament yarns which has been subjected tostretching, heat treating, cohering by pasting, drying and laterallyextended in a parallel state where, for example, 200 to 300 filamentyarns are extended laterally to a width of 50 cm.

3. Warped parallel yarn layer of filament yarns and spun yarns andparallel yarn layer of dyed and processed yarns thereof.

4. Parallel monoaxilly stretched tape layer, having been stretched infiat and parallel arrangement, and parallel split yarn layer thereofhaving been subjected to a splitting process.

5. Split fiber web in a reticular structure obtained by subjecting abroad monoaxially stretched film to a splitting process; a non-wovenfabric of split fibers which is obtained by further extending said splitfibers web to a definite broadness and whose web fiber arrangement isfixed by an adhesive binder; and non-woven fabric of split fibers havingwarp and weft construction and prepared from said split fiber web wherethe warp and wefi layers are fixed together.

Group B: Film and sheet such as:

6. Non-stretched film of thermoplastic polymer whose irregularity inthickness is generally in a range of t 5 30 percent when molded byextrusion.

7. Broad, monoaxially stretched film.

8. Biaxially stretched film.

9. Processed films and laminates of the films (6), (7) and The"Yarn-like material" used in the present invention means a narrow andelongated consecutive yarn-form product having a good dimensionalstability in a longitudinal direction and a little elastic bulkiness inthe direction of thickness, and includes, for example:

i. Spun yarn, filament yarn and split-fiber yarn having a suitablethickness; a thread, cord and string prepared by doubling and twistingthese yarns.

ii. Yarn prepared by doubling and twisting straight yarn together withother yarn in a bulky manner to endow an elastic bulkiness to thethickness direction of the yarn, the yarn twisted together with crimpedyarn and flufi'ed yarn.

iii. Tape, string and bristle, of ordinary or foamed structure,

etc.

The thin layer material, as explained above, has always some extent ofdeviations 5 30 percent) in thikness along both lateral and longitudinaldirections in its manufacturing and processing processes, but anoccurence of such irregularities in thickness is an inevitablephenomenon. When such a thin layer material is wound up plainly, as itis, under a tension, an irregularity in diameter of the wound roll, thatis, convexed parts and concaved parts appears along the entire width dueto the irregularity of the material in thickness when a considerablylong thin layer material is wound up. Tension at every convex partbecomes higher, and such a higher tension gives an unfavorable influenceupon the quality of wound-up product. Therefore, the plain winding ofsuch a thin layer material, whose length exceeds several 1000 meters,has been heretofore regarded as being impossible, and such a rollproduct has not been available commercially. Of course, it is possibleto make the irregularity in thickness of the thin layer material beabsorbed in a clearance between the wound layers if the winding tensionis made lower and a loose winding-up is carried out. Then no irreguarityappears on the surface of the wound roll, but in that case the wound-upcylindrical roll has such disadvantages that the wound-up layers areliable to slip in a longitudinal direction of the winding core, that istelescoping, and a winding deformation and roll collapse take placeremarkably. Therefore, the winding-up of long thin layer material hasnot been practically effected yet.

Accordingly, it is an object of the present invention to provide amethod for winding up a sufficiently long, thin layer material to form awound cylindrical roll of large diameter without the above-mentioneddisadvantages in effecting plain winding-up of such a thin layermaterial having a broad width and irregularities in thickness in whichthe yarn-like material inserted into between one layer and another,protects the side faces of the wound layers, prevents the roll fromgetting out of its initially wound up form and makes sure unwindingoperation.

Now, the present method will be explained in detail, referring to theaccompanying drawings:

FIG. la shows a state where a yarn-like material is supplied onto a thinlayer material while being reciprocatingly overtraversed to a widthgreater than the width of the thin layer material, which has a broadwidth;

FIG. lb shows how the over-traversed yarn-like material is wound over awinding core with an increase in the winding diameter of the thin layermaterial roll',

FIG. 2 shows a state where the yarn-like material, which becomes a chordover the side face of the wound cylinder when the thin layer material iswound onto the winding core, is piled up in layers, if the windingdiameter is smaller;

FIG. 3 shows a schematic plan view of a winding apparatus as an example.

FIG. 1a is a plan view of the wound-up thin layer material, which hasbeen unfolded into a plane. With the progress of a thin layer material 1of a width W, a yarn-like material 2 crosses the thin layer material atan angle 0 to the travelling direction of thin layer material and isplaced on the thin layer material to the extent of length L. Theyarn-like material leaves the thin layer material at a point 3 at theleft edge of the thin layer material and is over-traversed up to a point4 in the forward course. Then, in the backward course, the yarn-likematerial is placed again on the thin layer material at a point at theleft edge of the thin layer material, At that time, the yarn-likematerial constituting two sides of a triangle as shown by the dottedline from the points 3, through 4 to 5 goes along the side surface ofthe wound material as a chord from point 3 to point 5 as indicated in afull line in the drawing, owing to a tension applied to the yarn-likematerial. ln the case where its length l is larger than thecircumference of the winding core, the yarn-like material, at theinitial stage of winding, comes in touch with the winding core 6 afterit leaves the edge of the thin layer material and advances along theside surface thereof, as shown by I, in FIG. lb and is wound around thewinding core. When the winding diameter increases from d, to d,, I,further becomes 1, in the U form from the y form on the winding core.With further increase in the winding diameter, the contact length of 1,,(lindicates arbitral chord of I) with the winding core gradually becomesshort, and finally 1,, leaves the winding core after it has taken atangential line form, and then takes a chord form. That is to say, withthe increase in the winding diameter, a degree of opening of theV-shaped angle formed by the yarn-like material increases, and I,becomes a tangential line to the winding core at the winding diameterd,. Thereafter, 1,, becomes an arc chord to the winding circumferencewithout any contact with the winding core. With further increase in thewinding diameter, the chord 1,, appears more than once at the side faceof the wound roll. That is, the chord 1,, appears twice as 1 on one sideface of the wound cylinder at some winding diameter, as shown in thedrawing. At that time, 1, appears twice at the other side face thereof.In other words, L is placed more than four times on the thin layermaterial by one round. With further increase in the winding diameter,the numbers of I,, and L by one round are increased, though not shown inthe drawings. In the wound up state, 1,, at the side face of the woundcylinder lies far from the edge part of the wound cylinder andapproaches the edge part with greater inclination. With the increase ofwinding diameter the inclination of 1,, becomes smaller. From the pointwhere 1,, takes a tangential line form to the winding core, 1,, runsalmost straight along the side face of the wound cylinder. Accordingly,as shown in FIG. 2, the wound form is such that nearer the wound chord1,, to the winding core 6, the thicker the piling of 1,,.

FIG. 3 shows one embodiment of an apparatus for winding up a thin layermaterial. A yarn-like material 2 is supplied from a bobbin 7, and passesthrough resistance rods 8 and 8' to give a proper tension thereto,through a guide 9 provided with a coil spring to keep a tension almostconstant, even if a pulling out speed of the yarn-like material ischanged, for instance, at the time of over-traversing, and through a tipguide 12 at a traverse rod ll, whose root end is supported by a pivotl0, and reci rocatingly traversed over a cylindrical roll of the thinlayer l3, which has been already wound up. The yarn-like material isover-traversed beyond the width of the wound thin layer material andreciprocatingly moves between points 4 and 4'. The yarn-like material iscontinuously pulled out as the wound roll revolves and inserted intobetween one layer and another of the thin layer material at an inclinedangle. The shape, which the over-traversed yarn-like material takes atboth the side faces of the cylindrical wound-up layer, has been alreadyexplained above, referring to FIG. lb. The change in the supply speed ofthe yarn-like material according to the change in the form of I, fromthe points 3, through 4 to 5 is adjusted by elongation or contracting ofthe coil spring and the yarn-like material is supplied under an almostuniform tension. Any other suitable method for traversing the yarn-likematerial can also be employed.

The first object and effect of inserting the yarn-like material inbetween one layer and another of the wound cylindrical roll is toprovide an inclined clearance between the layers by insertion of theyarn-like material which allows an irregularity in the thickness of thethin layer material to be absorbed in the clearance and thus makes itpossible to wind up a considerably lengths of thin layer material into acylindrical roll, because the yarn-like material, even if inserted at aconstant pitch, is inserted many times into each neighboring layers andscattered in an inclined form between each layer of the wound roll atsome winding diameter, since the winding diameter of the thin layermaterial increases on each round and the inserting position of theyarn-like material is consequently changed.

The second object and effect is, as explained, referring to the drawing,to provide an action which protects an edge part of the wound layers ofthe thin layer material by the use of wound chord layers at the sidefaces of the cylindrical wound roll.

The third object and effect is to completely prevent a winding collapse,because the side face of the wound cylinder are protected from slippingby the wound chord in accordance with the present invention. In the casewhere there are many irregularities in the thickness of the thin layermaterial, it is a usual practice to loosen the winding tension so as toabsorb the irregularities and effect plain winding up of the thin layermaterial without inserting the yarn-like material as in the presentinvention. However, in case where a long, thin layer material is woundup into a roll of larger diameter, the wound layers are liable to slipout and sometimes are transformed into a shape like a telescope. Thatis, winding deformation and roll collapse often occur in the usualwinding practice.

The fourth object and effect is to make sure that the unwindingoperation is without any damage to remaining or newly developed fluff,which is particularly important in the case where the thin layermaterial is a broad, parallel filament or yarn layer, because, when theyarn-like material is inserted into between the layers at a constantpitch, the fluffs, which are liable to remain or appear in the yarnlayer when unwinding the wound layers, are swept away and separated byyarnlike material unwound together with the thin layer material by aseparate means. For example, when an inclined and elongated continuousyarn-like material is inserted into between the layers one by one roundat the start to wind up the layer onto the winding core, the number ofinserted yarn-like material in each round is increased with an increasein the winding diameter from the start of winding. That is to say, thewound layer is subjected to sweeping by a number of the yarnlikematerial in one round, at the unwinding, in the case of the wound layersof large diameter. Even if the unwinding comes near the winding core,the fluffs are swept away once in one turn.

Even if a rate of irregularity in the thickness of the thin layermaterial is equal throughout one winding process, an absolute value ofdimension in the irregularity in the thickness becomes larger with anincrease in the thickness of the thin layer material. Therefore, in thepresent invention, to absorb such irregularity in the thickness, atyarn-like material having a larger thickness must be used to make theclearance larger or winding-up must be effected under a low tension in arange not to allow the inserted yarn-like material to slip or move. Inthat case, use of a yarn-like material having an elastic bulkiness inthe thickness direction is more preferable and meets the object ofpreventing the wound layers and the yarn-like material from slipping,and also prevents a winding from deforming and a package fromcollapsing, whereby a long, thin layer material can be wound up into acylindrical roll of larger diameter.

As explained above, the thin layer material having a broad widthincludes the Group (A) of fibers and yarns and the Group (B) of filmsand sheets, and the present invention is applicable to any of thesegroups effectively, but there is some modification in application,depending upon the groups.

Now, further explanation will be made according to these groups:

First of all, explanation is made in case of tow of the Group (A) lNowadays the commercially available tow is supplied in a package of 50kg of crimped tows all prepared by a stuffer box method. When the tow ismade into short fiber sliver according to a tow spinning method, forexample, by

heating, stretching and cutting, the crimps are so stretched out thatthey have no recovering ability. Therefore, the significance to endowcrimps is merely to improve a clinging property of the fibers to eachother and has the object to make the handling thereof free from anytrouble in case of unpacking, etc. in subsequent processes. However, thecrimped tow is bulky and therefore its shipping form is a package offibers, whose apparent winding density is as low as 0.26 0.30. As aresult, its packaging cost and transportation cost become higher. Thoughthe parallel fibers may be directly wound up onto a bobbin, flufls areliable to be generated at the unwinding, and once fiuffs are generated,these fluffs induce another fiuffs. Consequently, smooth unwinding isimpossible. When wound up by traversing, the tow undergoes falsetwisting of a long pitch between each turning back and the parallelproperties of the fibers are sometimes damaged. Thus, the tow has notyet been practically wound up.

Filament tows of polyester, nylon, polypropylene, polyacrylic, etc. havebeen heretofore produced and procescd as a broad, thin layer material of30 50 cm of a tow of 300,000 to 500,000 d. not only up to a stretchingstep, but also to a heat-treating step except for the polyacrylicfibers, and if they can be plainly wound up and unwound without anytrouble, the shipping forms will become smaller and the transportationcost will become cheaper. Thus, an invention of a better method forenabling the plain winding-up and easy unwinding has been longed for.

For tows subjected to dyeing processing in a bundled state and thenlaterally extended or for tows whose crimps are fixed under a saturatedvapor pressure, temporarily stretched and set in order to leaveremaining crimps suitable for the spinnability under the atmosphericpressure steam at l C to avoid the trouble in the subsequent spinningcaused by excessive crimps and then laterally extended to a width of 3050 cm, while keeping the parallel arrangement of the fibers as they are,an appearance of a better winding process has been also longed for.

If a tow of 300,000 to 500,000 d. can be plainly wound up in aparalleland laterally extended state of the fibers to a width of about50 cm, without any trouble to the unwinding in a noncrimped state, it ispossible to wind up and package the fiber layer at an apparent windingdensity of 0.5 0.8, that is, in a volume A to /5 smaller than thepackaged volume of the crimped tow by conventional practice. However, inpractice, it has been impossible to effect a sure unwinding because ofremaining fluffs, and as already explained above, such winding-up hasnot been practically employed yet. When a narrow bundle of tows is woundup to a broad width by traversing, false twisting is applied to the towsas aforementioned, and a disturbance appears in arrangement or in theparallel properties of the fibers. Or, a damage due to fluff appears incase of unwinding. As these disadvantages are brought about, a packageof about 100 kg of crimped tow in a carton box is employed in thecurrent practice.

However, by employing the method of the present invention, the fluffsare swept away by the inserted yarn-like material at the unwinding, andtherefore the unwinding can be effected without any trouble. That is, acylindrical plain winding-up can be effected. For example, a towlaterally extended to a width of 50 cm is plainly wound up onto awinding core having a diameter of cm, and the wound cylindrical rollhaving an apparent winding density of 0.4] can be obtained when thewinding diameter reaches 80 cm. That is, fibers of I00 kg can be plainlywound up. In view of the fact that it is easy to effect windingup havingan apparent winding density of 0.5 0.8 in the ordinary winding-up oi thefibers and yarns, it is possible to provide a sufficient clearance forinserting the yarn-like material, when plain winding having such a lowapparent winding density as explained above, is eflected, and thepossibility for sufficiently absorbing the irregularities in thethickness by inserting a highly bulky, thick yarn-like material under alow tension can be given thereby. However, even in this case, there is afear of collapse of edge part towards the side faces of the wound layersin case of the parallel fiber layer. Such a fear can be overcome ifwinding is carried out by a device which enables to gradually narrow thewidth of the wound layers according to the increase in the thickness ofthe wound layers. For expanding or narrowing the width of the parallelfibers, another invention of the present inventors, "a method forexpanding or contracting a bundle of fibers and yarns" (U.S. ApplicationSer. No. 47775 filed on June 19, 1970) is one example of preferablemethods. Said method is useful for uniformly spreading or converging aband comprised of a great numbers of filaments by the step of placingsaid band transversely across and between the turns of a coil spring ofsubstantially uniform cross-section whereby the turns of the helixseparate the filaments comprising the band into a plurality of portions,altering the distance between the turns of the helix to correspondinglyenlarge or narrow the width of the band, and removing the band ofadjusted width from contact with said coil spring. According to saidmethod, the tow is extended to a larger width for the portion near thewinding core, and the extended width of the tow is gradually narrowedwith an increase in the winding diameter. That is to say, if the fibersor yarns are placed one upon another in a trapezoid form, a downwardcollapse of the edge part of the tow can be completely prevented. In anyway, when a bundle tow is extended, the irregularity in the thickness offibers along the entire extended width is sometimes increased to aconsiderable extent. In such a case, by making the thickness of theyarn-like material as large as 3,000 5,000 11., or by using a highlybulky yarn-like material and loosening a winding tension, the wound-upform can be kept in an almost cylindrical state, without causing windingdeformation and collapse, even when about 100 kg of the layer having awidth of 50 cm is wound up to a larger diameter of 70 cm. Further,unwinding can be carried out smoothly. Of course, when the thin layersof the fibers are unwound, the unwound yarn-like material can be reused,if it is wound onto a bobbin driven by a torque motor. The amount of theyarn-like material is, in most cases, less than I percent of the amountof a tow of fibers. Even when the recovered yarn-like material is thrownaway, the packaging cost will be cheaper.

Now, explanation will be given to the case of filament yarns of Group(A) (2). In case of nylon, polyester, etc., the yarns after spinning arestretched and twisted yarn by yarn in a draw-twister and wound up ontobobbins, each yarn on each bobbin. Such a procedure has been heretoforeused, but required much labor for doffing the bobbins. However, if 200yarns are arranged in parallel at a pitch of 5 mm within a width of l m,stretched, thereafter heattreated and pasted with a polyvinyl alcoholtype adhesive for each yarn to prepare parallel pasted cohered yarns andkg of the yarns are wound up in a parallel state of 200 yarns accordingto the present method in which the yarn-like material is inserted, theweight of each yarn becomes 500 g and it has a sufficient length forpractical usages. Thus it will be a method for producing the yarns whichrequires considerably less labor than the conventional methods in whichyarns are applied to a draw-twister which deals with yarns one by one.The yarns, which have been passed through the stretching at a width of lm, heat treatment, cohesion-by-pasting, and drying, can be wound upafter being passed through a comb at a pitch of 5 mm for yarns one byone, where the comb is inclined by 60 from the parallel position to thewinding core, so that the winding width becomes 50 em. if the angle ofthe comb is further increased with an increase in the winding diameter,the winding width can be properly narrowed from 50 cm to 40 cm. If thewinding width is narrowed while inserting the yarn-like material intobetween the layers, no disadvantage of winding collapse at the edge partof the wound roll is brought about. Twisting can be applied to theyarns, if necessary, after the yarns are divided into 200 ends, and thenwound up onto each bobbin.

The group (A) (3), (4), etc. are treated in the quite same manner as inthe case of the group (A) (2). However, in the case of a split fiber webin a reticular structure and non-woven fabric prepared therefrom of thefibers are interconnected throughout the entire width to form areticular structure and further, the non-woven fabric of laminatedlayers of their warps and wefts differs from ordinary filaments andyarns in fiber arrangement where there is no fear of winding deformationand edge collapse, even when the winding width is not narrowed with theincrease in the winding diameter so long as they are wound according tothe present method.

Also in the case of film system of the group (B) consisted of (6), (7),(8), etc., there is no fear of the edge collapse, and therefore, thelayer is only plainly wound up at a definite width while inserting theyarn-like material into between the layers according to the presentmethod. Even when there are large irregularities in thickness, thewinding up of a long film-lilte material can be done easily byincreasing the thickness of the yarn-like material, using a yarn havinga high modulus of elasticity of bulkiness, and loosening windingtension. There is no trouble in the unwinding operation in the case ofthe film like material, but an irregularity corresponding to thethickness of the yarn-like material is apt to develop at the portion ofthe film, with which the yarn-like material is in contact. In this case,by passing the film over a heated drum and ironing it, the irregularityis removed by heat and a smoother film can be obtained. Therefore, whena stretched film is used as a base film for coating in the preparationof a synthetic paper, it is necessary to pass the base film over theheated drum and subject it to an ironing process for smoothening beforecoating for synthetic paper. Namely in the case of the coated syntheticpaper manufacture, a base film roll wound as long as from 10,000 toseveral ten thousand meters is necessary for economical commercialproduction. Therefore a long base film wound up to a roll of largediameter according to the present invention, maybe subjected to anironing process using a heated drum in a unwinding process to effectsmoothening of irregular film for coating it in the next step. Thus thefilm of large wound diameter, which has been wound up according to thepresent method can be used without any trouble as a base film for thesynthetic paper.

Further, in the case of a roll of small wound up diameter such as thoseof conventional products on market, for example, the wound up 1000 mlong material, the film once wound up to a larger diameter according tothe present invention is passed over a heated drum to form a flat filmand then plainly wound up again to a smaller diameter of 1000 m-longmaterial under a low winding tension according to the conventionalmethod, whereby the winding can be effected without any irregularity ofwound-up state even through there is a little irregularity in thethickness, and there is no fear of winding collapse. When the thin layermaterial is generally a fibrous product, it is, in many cases,sufficient that the winding width is 50 60 cm, the winding diameter isless than I m and the weight of one wound-up roll is about I00 kg, butwhen a biaxially stretched film is used as a base film for coatedsynthetic paper, the desirable width of the film is l to 2 m. Therefore,it is expected that the winding width becomes larger and the weight ofone wound-up roll becomes 500 to I000 kg. if the apparent windingdensity of the wound-up layer is 0.75 at a winding width of 1.65 m and awinding diameter of 1.0 m with an inserted yarn-like material intobetween the layers, the weight of wound-up layer will be about one ton,and the film length be about 50,000m at an assumption of 20 g/m. Thereis no need of such along wound up length but, it can be used as a basefilm for a raw material in the coated synthetic paper manufacture byoff-machine procedure sufficiently, so long as the layer has a length ofat least 10,000 m, because the raw paper for the ordinary coat paper andthe art paper is 6000 to 7000 m long.

As to the inclined crossing angle 9 of the yarn-like material, 9 can bechanged in a wide range, depending upon the property and kind of thethin layer material, the property and kind of the yarn-like material,winding core diameter, wound-up diameter, etc. For the thin layermaterial of the group (A), a

relatively large an e is selected, and for the thin layer material ofthe group (B a relatively small angle is selected. Sometimes, an angleof 10 or less is employed. lt is not always necessary that the inclinedcrossing angle 0 be constant by one-round winding. For example, it ispossible to make the inclined crossing angle larger at the start ofwinding-up to make the yarn-like material be less wound-up around thewinding core. and then gradually make the angle smaller.

The inclined crossing angle 0 is determined by a relation between thewinding speed of the thin layer material and the traversing speed of theyarn-like material. Further, the length of chord of the yarn-likematerial formed on the side face of the wound roll is determined by theexcess degree of traversing, winding speed and traversing speed.Further, it is properly selected in view of the properties and kinds ofthe thin layer material, the properties and kinds of the yarn-likematerial, the diameter of the winding core, the winding diameter, etc.

What is claimed is:

1. An improved method for minimizing telescoping in the winding up of abroad width of thin layer material upon a winding core so as to therebyproduce a large generally cylindrical roll which comprises:

a. continuously supplying an elongated continuous yarn-like materialbetween I. the exterior surface of a layer of material that has justbeen wound and 2. the under surface of a layer that is about to be woundinto face to face contact with said wound layer,

b. traversing said yarn-like material back and forth across thecylindrical surface portion of said material being wound, and

guiding said yarn-like material that has traversed the cylindricalsurface portion in one direction across a portion of an end section ofsaid cylindrical roll before said yarn-like material reverses itsdirection and traverses across the cylindrical surface portion of saidmaterial being wound in the opposite direction.

1. An improved method for minimizing telescoping in the winding up of abroad width of thin layer material upon a winding core so as to therebyproduce a large generally cylindrical roll which comprises: a.continuously supplying an elongated continuous yarn-like materialbetween
 1. the exterior surface of a layer of material that has justbeen wound and
 2. the under surface of a layer that is about to be woundinto face to face contact with said wound layer, b. traversing saidyarn-like material back and forth across the cylindrical surface portionof said material being wound, and c. guiding said yarn-like materialthat has traversed the cylindrical surface portion in one directionacross a portion of an end section of said cylindrical roll before saidyarnlike material reverses its direction and traverses across thecylindrical surface portion of said material being wound in the oppositedirection.
 2. the under surface of a layer that is about to be woundinto face to face contact with said wound layer, b. traversing saidyarn-like material back and forth across the cylindrical surface portionof said material being wound, and c. guiding said yarn-like materialthat has traversed the cylindrical surface portion in one directionacross a portion of an end section of said cylindrical roll before saidyarn-like material reverses its direction and traverses across thecylindrical surface portion of said material being wound in the oppositedirection.